Dry AMD therapy evolves with photobiomodulation

Take-home message: Non-invasive photobiomodulation may help dry age-related macular degeneration by causing regression of drusen and improving retinal function with benefits in visual acuity and contrast sensitivity.

By Lynda Charters; Reviewed by Graham Merry, MBBS, and Marion R. Munk, MD, PhD

Photobiomodulation (PBM) may be a new non-invasive, light-based treatment for patients with dry age-related macular degeneration (AMD) who, until today, have no real therapeutic options.

The technology (under development by LumiThera Inc.) may help improve vision in this patient population by causing regression of drusen with parallel improvements in visual acuity and contrast sensitivity, according to TORPA II study outcomes.

Marion R. Munk, MD, PhD, of the Department of Ophthalmology, Inselspital University Hospital, Berne, Switzerland, and Graham Merry, MBBS, from Photospectra Health Sciences Inc., Toronto, were part of the investigative team that evaluated the technology.

They described this novel treatment for dry AMD used in a study to assess the functional and anatomic benefits of PBM therapy. The technology—which uses light-emitting diodes of red (670 nm), yellow (590 nm), and infrared (790 nm) wavelengths—was applied to both eyes of 24 patients three times weekly over 3 weeks.

The hope was that the treatment would stimulate cellular function in the retina. Primary outcome measurements were Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (BCVA) and contrast sensitivity measurements, as well as changes of retinal drusen volume on optical coherence tomography (OCT) images after treatment.

Merry reported that ETDRS BCVA improved by a mean of +5.9 letters (p < 0.001) in 48% of eyes from six to 10 letters, >1 line of vision, and in 12% from 11 to 15 letters, >2 lines of vision.

Contrast sensitivity improved by +0.11 log unit at 3 cycles per degree (p = 0.02) immediately after treatment. Gains in both BCVA and contrast sensitivity were maintained for 3 months.

In concert with those changes, investigators observed a significant decrease in drusen volume by 0.024 mm³ (p < 0.001) and in central drusen thickness by a mean of 3.78 µm (p < 0.001) immediately after treatment that also was maintained for 3 months. Investigators found the mean central drusen thickness decreased without new formation of geographic atrophy.

Functional, anatomic benefits

This is the “first instance of significant improvement in both the functional—i.e., BCVA and contrast sensitivity—and objective anatomic—i.e., drusen volume seen on OCT images and decreased central drusen thickness—findings in patients with dry AMD who underwent PBM therapy,” Merry said. “Results indicated a sustained and potential disease-modifying effect following a short, non-invasive photobiomodulation treatment course.”

The investigators believe these results provided a basis for further clinical trials with this non-invasive treatment approach.

The LIGHTSITE study—a 30-subject, randomized, double-masked, sham-controlled clinical trial—currently is enrolling patients with dry AMD in Canada. The study is partially funded by a NIH National Eye Institute grant to LumiThera, and will utilize the LT-300 instrument and multi-wavelength protocol.

Graham Merry, MBBS

E: gmerry@lumithera.com

Marion R. Munk, MD, PhD

E: marion_munk@hotmail.com

Both investigators receive financial support from LumiThera Inc.